The present invention relates generally to systems for continuously infusing medication into a patient and, more particularly, to apparatus for the configuration of such a system for automatic operation in a selected mode.
Until recently there were two major techniques available for delivering drugs to a patient when the drugs cannot be orally administered. The first technique is to inject the drug into the patient with a syringe and needle to deliver an appreciable dose at relatively infrequent intervals. This technique is not always satisfactory, particularly when the drug being injected is potentially lethal, possibly has undesirable side effects when given in a large dosage, or must be delivered more or less continuously to arrive at a desired therapeutic result. This technique leaves much to be desired. The risks of overdosage or harmful side effects may be reduced by giving smaller injections at more frequent intervals, an inconvenient and not altogether satisfactory alternative.
The need for delivering a drug more or less continuously to achieve a desired therapeutic effect gives rise to the second technique, which involves a continuous delivery of medication to the patient, typically through an intravenous drip. Medication may also be administered using an intravenous system with an injection into a complicated and cumbersome interconnection of Iv tubes, hoses, and other components. Drop counters are used to measure the amount of fluid delivered, and medications are often delivered in a large dose through injection into the Iv lines, with the medication being somewhat dilute by the fluid.
A relatively recent alternative to these two techniques of administering medication to a patient is the medication infusion pump. A valuable and much needed development, the medication infusion pump can be used to administer drugs to a patient in small, carefully measured doses at frequent intervals or, with some devices, slowly but uninterruptedly. A therapeutic regimen with an infusion pump can be controlled electronically to administer precisely measured quantities of a drug at precisely planned intervals to give a gradual infusion of medication into the patient. The infusion pump makes possible a closer approximation to the natural maintenance of biochemical balances in the body because of its operation in a repetitive small dose mode.
Disposability is an important consideration in the design of medication infusion systems. Parts of the system through which medication is pumped must be sterile, so that in most applications some of the equipment is used and then discarded. The disposable parts are typically replaced at regular intervals, typically on a daily basis. Disposability of the fluid pump portion of the infusion device is a highly desirable feature. It would be very convenient to design a fluid pump in the form of an attachable cassette of economical design which could easily be installed onto a main pumping unit. A cassette which uses a small number of parts, is easily mass productible, and is capable of delivering liquid medication or other therapeutic fluids with a high degree of precision is described in U. S. Patent application Ser. No. 127,383, entitled "Disposable Cassette for a Medication Infusion System." The contents of that application are incorporated herein by reference.
The disposable cassette which is referred to above includes a fluid pump affording a high degree of accuracy in fluid delivery, with the degree of accuracy being maintained throughout the life of the product. The cassette also provides means for conveniently and easily priming the pump, and includes a bubble trap to prevent the frequent shutdowns and alarms which are a problem with presently available pumps. The cassette also includes additional devices such as pressure sensing means and bubble detecting means which in conventional medication infusion systems constitute separate assemblies.
A fluid monitoring and control system for use with disposable cassettes is needed to ensure accurate and safe delivery of therapeutic fluids. The design of such a system requires careful attention to factors involved in the accuracy of fluid delivery, and instrument monitoring functions are necessary to insure safe operation of the system.
There has been a long-felt but unresolved need for the development of a medication infusion management system that can be used for patient care in both hospitals and home health care applications. A desirable system would provide a reliable and improved product for current applications to encourage the use of new therapeutic techniques, reduce the cost of hospitalization by improving care and decreasing labor and inventory costs, and would be versatile enough to allow intra-arterial and subcutaneous infusions. Primary requirements of such a system would be volumetric accuracy, state-of-the-art safety functions, and a capacity for independently controlling more than one pumping channel, each with a separate line to the patient.
Ideally the pump of the improved medication infusion system would be substantially smaller and lighter than current hospital pumps while at the same time incorporating multiple pumping channels. Moreover, it is desirable to be able to configure selected system parameters and to monitor displayed information related to the needs and performance of a given system, thereby optimizing system operation. Together with the possibility of extended battery-powered operation, these features may be incorporated in a device that is particularly well suited to ambulatory care, intensive care, emergency transport, emergency care, or operating room use, as needed.
A system with the capacity for multiple pumping channels, a variety of disposable configurations, a maintenance mode, and a library of software functions could combine the capabilities of several currently available devices into one single unit. For example, the need in a hospital for separate syringe pumps, PCA pumps, neonatal pumps, general purpose pumps, and computer communications pumps could be eliminated in favor of one system that could satisfy the requirements for all these devices on a selective basis.
The capability of a medication infusion system to operate interchangeably on a selective basis in the emulation of the different types of pumps listed above would represent a significant cost savings for hospital administration with the elimination or substantial reduction of some of the costs associated with the use of medication infusion systems. A major reduction in inventory costs associated with infusion systems is possible if one pump apparatus can replace a plurality of different specific types. Also, the capability of a single medication infusion system to operate with a plurality of channels reduces equipment cost. Other cost benefits may result from a reduction in the number of different disposable peripherals which are required for the infusion system, a reduction in cost of required maintenance and an easing of personnel training requirements.